Disable any services that use lots of resources (memory, CPU, disk) during playback. Personally I don't find much difference having services like spotlight enabled, most of these are very well optimized already.

The first recommendation I would make is to get an external DAC. While the internal audio on most Macs is decent, an external DAC with a good pair of headphones makes a world of difference! The second recommendation I have is to use digital volume judiciously. Turning the digital volume down in an audio player and then turning the DAC's volume up is counterproductive. Finally, I would recommend using only lossless formats like FLAC or Apple Lossless. Bandwidth and disk space are so cheap these days that there is no reason to use lossy formats.

Use some audiophile music player software on a good quality computer. And have a mains filter for the audio equipment and keep computer mains separate.

If DAC is directly connected to the player computer, preferably use a computer purpose-built for audio use. Networked DAC connections help isolating player computer from the DAC, and make DAC(s) easily accessible from different computers.

We recommend using dedicated operating system installation for playback with absolutely no software installed except for vital drivers and player. On hardware side: high quality USB-to-S/PDIF converter between PC and DAC in most cases gives better sound than using built-in USB input in DAC, quality USB cable also makes a big difference even with asynchronous USB interfaces. Power cables and anti-vibration platforms also matter in computer audio systems.

This stuff is covered in the documentation accompanying Pure Music. Getting a system up and running is not a big deal, just making some simple, one time settings to the system preferences, and in the case of Pure Music, activating Memory Play and Upsampling, if desired.

An overlooked issue, I think, is what happens when you have your system running perfectly with great sound and one day it “stops working?” First of all, a computer audio system or a music player application will never change behavior or stop working on its own (barring a severe hardware failure, such as a hard drive crash). For something to change, the user *must* make some change.

For example, a user installs a new OS version, and the player behaves quirkily afterwards. Solution: don’t jump in and play music as soon as you have upgraded; the computer needs time to perform some initial tasks that can interrupt normal operations (as mentioned above).

One not so basic tip, but of extreme importance in a digital playback system, is gain structure. This is not a problem if using an analog preamplifier to control the volume. However it is perfectly reasonable to connect a DAC directly to a power amplifier, and use the player volume control. We do this in our expo show systems, and our reference room. With high sensitivity speakers, this might mean setting the digital volume control below its optimum range (as explained on the Getting Started With Computer Audio section of our website). This will have an adverse impact on the sound, and the only solution is an analog attenuator. We have been showing a prototype of an active analog attenuator designed to address this issue at audio expos since late last year, and this product will go into production in about two months.